Fluid operated switch



Oct. 7, 1958 J. RABINOW 2,855,473

FLUID OPERATED SWITCH Filed Dec. 9. 1955 T177 5 INVENTOR.

c/acob Rab/now 32 WXV/ After-neg United States Patent 2,855,473 FLUIDOPERATED SWITCH Jacob Rabinow, Takoma Park, Md. Application December 9,1955, Serial No. 552,184 7 Claims. (Cl. 20019) This invention relates tomulti-contact electrical switches in which a moving fluid is used tooperate the contacting members.

There are many fields in the electrical arts where high speed,multi-contact switches are of great importance. Among these are: the artof analog-to-digital converters, telemetering commutators, telephoneswitches, computer switches, and so on.

As is well known, most switches suitable for high speed operation havelimited life and there exists a need for switches that can makeand-breaka multiplicity of circuits for thousands, millions, and even billions ofcycles.

In the switch described in this specification I shall describe a simpledevice capable of very long life and foolproof operation. The switchuses a gas or a liquid as the actuating means for the contacts,resulting in a minimum of mechanical shock an wear in the mechanism.

The main object of my invention is to produce an electrical switchcapable of operating for a great number of cycles.

Another object of my invention is to produce a switch capable ofoperating at a very high rate of speed.

Another object of my invention is to produce a switch of relativelysimple and inexpensive construction.

Still another object is the provision of high-speed switch means havinga plurality of adjacent contact operable by direct fluid pressure atvery high speed and in very rapid succession. A further object is theprovision of a series of adjacent switches and means for delivering ajet of high-velocity fluid in rapid succession to different ones of saidswitches to actuate them.

According to the invention, a series of switches is provided, eachswitch having at least one resilient switch blade adapted to be acted ondirectly by a jet of fluid, which may be gas or liquid, to move saidresilient blade into contact with an opposite contact element of theswitch while the jet is acting on the blade, the blade disengagingitself from said contact by its own resilience or by anoppositely-directed force on said blade as soon as the jet pressure isremoved. The jet may be applied to the blades in rapid succession by amoving nozzle. If the blades are arranged in a circle or on an arc, thenozzle may be a rotating one, in which case the operation may be cyclic.

The specific nature of the invention, as Well as other Fig. 5 is aschematic diagram of a modified form of theinvention.

Fig. 1 shows a schematic view of my invention. A jet of air (or othergas) is moved across a plurality of switch contacts 2, 2', and 3, 3',etc., so that it causes the various contacts to close, one after theother. This jet may be delivered by a rotating nozzle 4, supplied withair under pressure from pipe 6 through coupling 7. Because the air canbe given a very high velocity as it leaves the nozzle, the operation ofthe switch can be made very rapid.

It will be noted that there is relatively little motion between themating contacts 2, 2, etc. Depending on the design of the spring contact2, a suitable amount of wipe can be designed into the mating contacts,if desired.

For many types of use, very little or no wiping action is required, andan open-circuit contact separation of only a few thousandths or V1000 ofan inch is required, so that very little force or pressure is requiredeven for high speed operation. Under these conditions, by using suitableknown long-wearing contact materials, the switch can be made capable ofextremely long life, in the order of millions or even billions ofcycles.

Fig. 2 shows a more practical design of an air operated switch. Here twocontacts, 12 and 13, are operated simultaneously by the two jets 14 and15. This is shown by way of example only, as more than two jets may beused. Very many different arrangements of contacts may be used. The air,being non-conductive, permits isolation of each switch element, ifdesired.

Any suitable source of compressed air can be used, except that forlong-time operation the air should be suitably cleaned. Means for doingthis are now well known. An inert gas can be used instead of air and,under some circumstances, leads to improved performance of the contactsand longer life. Instead of air under pressure to operate the contacts,vacuum applied to the exhaust pipe 16 of the case 17, as shown in Fig.2, will also produce the desired result. Finally, of course, the gas canbe recirculated by a suitable pump as shown in Fig. 4. The pump is shownas a separate unit driven by the same shaft 18 that operates the switch,but normally it would be made an integral part of the switch mechanism,and the whole assembly can be totally enclosed to keep out dirt,moisture, etc.

The details of the actual contacts are shown in Fig. 3. An insulatingplate which may be the back of casing 17 carries a large number of thestationary contacts 12, 13' which may be of the printed circuit variety,if desired. A multi-fingered spring member 21 is located immediatelyadjacent to these contacts 12' so that one finger 12 of the springmember 21 is located over each of the stationary contacts. Still furtherahead of the spring is a backstop plate 19 which can be made of anysuitable material and which serves a triple purpose.

This plate 19 preloads the spring fingers, so that in the open positionthey press lightly against the face of this plate. This prevents theiroscillating freely in air and prevents accidental contact closure due toresonant vibrations.

The plate also serves to accurately position the spring contacts 12 andthus control the gap spacing between the stationary and moving contacts.

And, thirdly, the plate can be provided with holes 22 so that the airjet is interrupted between contacts, making possible a definite breakbefore make of the contacts, if desired, even through the contacts arevery close together.

All of the switches illustrated can be operated by liquid as well asgas, but the totally enclosed switch of Fig. 2 is perhaps best suitedfor this purpose. If the switch is operated by a liquid, such as forinstance, a light machine oil, the whole case 17 can be filled with theliquid. If desired, the case can be kept substantially empty of liquidby having the oil continuously pumped out of the case and back into thenozzles.

I found in my experiments with a switch of this type, that submergingingthe contacts reduced contact bounce because of the damping property ofthe liquid. The use of a suitable liquid will enable the switch tohandle higher voltages without breakdown and will require a smaller pumpto achieve satisfactory operation.

Fig. 5 shows a slightly different arrangement of my switch wherein thenozzles 26 are stationary, but an air-commutator is used to feed the air(or other fluid) to the nozzles in succession. The revolving cyclinder27 is provided with at least one hole 28. The cylinder is closely fittedinto the bored hole in the nozzle casing 29. As the shaft 31 revolves,the cylinder revolves with it. Thus the hole 28 lines up successivelywith passages 32 connecting the air to the nozzles in sequence.

While I show the contacts arrayed radially and the jets acting along aline parallel to the axis of rotation of the central shaft, it should beunderstood that radial jets can be employed with the contacts arrangedat right angle to the jet axis.

In the figures of this specification, I show simple single pole-singlethrow switch elements for the sake of clarity. It should be obvious tothe users of such switches that other contact combinations are possibleas well. By using an insulating plate 19a as shown in Fig. 2a, andmounting an additional set of stationary contacts 20 on this plate,single pole-double throw action can be achieved. In general, the contactarrangements so well known in the relay art today can be used in theswitches of this invention. As in the case of the relays, the stationarycontacts need not be truly rigidly mounted. They can be mounted onrelatively springy supports so as to provide more wipe as the contactsclose and to enable the switch design to use stacks of contacts behindeach other.

In Figs. 1 and 2, the fluid is shown as acting directly against themovable contacts. If desired, a flexible diaphragm 25 can be introducedbetween the movable contacts and the nozzles 26, as shown in Fig. 5. Thefluid would then impinge on this diaphragm, and through it operate thecontacts, without coming into contact with the switch elements.

In Fig. 3 the spring contact members 12 are all shown conductivelyconnected to plate 21; however, it will be understood that these contactmembers, or some of them, may also be insulated from each other toprovide independent control of separate circuits, where desired.

It will be apparent that the embodiments shown are only exemplary andthat various modifications can be made in construction and arrangementwithin the scope of my invention as defined in the appended claims.

I claim:

1. An electrical switch comprising, a plurality of armately arrangedinsulatedly separated stationary contacts, a like plurality ofconductive resilient radial finger-like contact members each extendingover and in closely spaced relationship with a respective one of saidstationary contacts, a nozzle for directing a fluid stream in thedirection of at least one of said radial finger-like contact members,means for angularly sweeping said nozzle successively across saidfinger-like contact members, and means for furnishing fluid underpressure to said nozzle during the sweep thereof, whereby saidfinger-like contact members are successively engaged and resilientlyseparated from the respective stationary contacts.

2. An electrical switch comprising, a plurality of circularly arrangedinsulately separated stationary contacts, a like plurality of relativelythin conductive resilient radially disposed finger-like movable contactseach extending over and in closely spaced relationship with a respectiveone of said stationary contacts, a nozzle for directing a fluid streamin the direction of one of said movable contacts, means for continuouslyrotating said nozzle successively across said movable contacts, andmeans for furnishing fluid under pressure to said nozzle during therotation thereof, whereby said finger-like movable contacts aresuccessively engaged and resiliently separated from the respectivestationary contacts.

3. An electrical switch comprising, a plurality of stationary contactscircularly disposed upon an insulating plate, a like plurality ofrelatively thin conductive resilient finger-like movable contactssecured to said insulating plate each extending radially over and inclosely spaced relationship with a respective one of said stationarycontacts, a nozzle for directing a fluid stream in the direction ofmotion of one of said movable contacts for engaging the respectivestationary contact, means for continuously rotating said nozzle,successively across said movable contacts, and means for furnishingfluid under pressure to said nozzle during rotation thereof, wherebysaid finger-like movable contacts are successively engaged anresiliently separated from the respective stationary contacts.

4. An electrical switch comprising, a plurality of stationary contactscircularly disposed upon an insulating plate, a like plurality ofrelatively thin conductive resilient finger-like movable contactssecured to said insulating plate, each of said movable contactsextending radially over and being normally upturned from said insulatingplate at the respective one of said stationary contacts, a nozzle fordirecting a fluid stream at one of said movable contacts in thedirection of the respective stationary contact, means for continuouslyrotating said nozzle successively across said movable contacts, andmeans for furnishing fluid under pressure to said nozzle during rotationthereof, whereby said finger-like movable contacts are successivelyengaged and resiliently separated from the respective stationarycontacts.

5. An electrical switch comprising, first and second parallel mutuallyspaced insulating plates, said first plate supporting a plurality ofcircularly disposed stationary contacts, a like plurality of relativelythin conductive finger-like movable contacts secured to said firstinsulating plate each extending radially and having a free end over arespective one of said stationary contacts, said free end of each ofsaid movable contacts being upturned into engagement with said secondinsulating plate, said second insulating plate being formed withopenings in the region of engagement with each of said movable contacts,a nozzle for directing a fluid stream at one of said openings in saidsecond insulating plate toward the respective movable contact, means forcontinuously rotating said nozzle successively across said openings insaid second insulating plate, and means for furnishing fluid underpressure to said nozzle during rotation thereof, whereby said movablecontacts are successively engaged and resiliently separated from therespective stationary contacts, said second insulating plate serving topreload and preclude oscillation of said movable contacts.

6. An electrical switch in accordance with claim 5 wherein said movablecontacts are formed as integral f radial extensions of a generally flatcircular conductive member secured to said first insulating plate withinsaid circularly disposed stationary contacts.

7. An electric switch in accordance with claim 5 wherein contact meansare provided on said second insulating plate for engaging each of saidmovable contacts.

References Cited in the file of this patent UNITED STATES PATENTS1,322,506 Austin Nov. 25, 1919 2,222,542 Robison Nov. 19, 1940 2,239,738Russell Apr. 29, 1941 2,379,197 Stubbins June 26, 1945 2,510,552 Carrollet al. June 6, 1950 2,773,665 Berger et al Dec. 11, 1956 2,773,951Finley et al. Dec. 11, 1956 FOREIGN PATENTS 192,704 Great Britain May 1,1924 194,404 Great Britain May 12, 1923

